Most of us know that cooking with oils is healthier than cooking with butter or margarine. However, it isn’t as commonly known that oils can actually lose their nutritional value at certain temperatures. Not only can oils lose some of their ability to lower your risk of heart disease, but they can also have an unpleasant taste if they get too hot.
Every type of oil has a certain temperature at which it will start to break down and lose some of its healthy properties. That temperature is called the smoke point because it's the temperature at which the oil will smoke and start producing toxic fumes and harmful free radicals.
It's important be aware of the smoke points of oils so you can choose the right oil for the job. Some oils are better suited for higher temperatures. A good rule of thumb is that the more refined the oil, the higher the smoke point.”
When cooking at high temperatures, stir-frying or roasting, it’s best to use corn, soybean, peanut, sesame and or vegetable oils because they have high smoke points. Olive, canola and grape seed oils are great choices for cooking with medium-high heat, such as sautéing. Flax seed and walnut oils have low smoking points, so it may be a healthier choice to use them in salad dressings, dips or marinades.
Reducing the amount of saturated fats and trans fats from your diet, such as from butter, margarine, lard and shortening, may help decrease total blood cholesterol levels, as well as low-density lipoprotein (LDL), which is known as bad cholesterol. This will help you prevent your risk of cardiovascular disease and Type 2 diabetes
Some people get enough oil in the foods they eat, such as from fish and nuts. For a chart of the amount of oils in common foods, visit http://www.choosemyplate.gov/.